Originally taken from DistroTube's instructions on installation:
https://www.youtube.com/watch?v=2n93ioqHf-U

Installing rtorrent, a simple terminal based torrenting client on Linux is relatively easy, install the binary from whichever main repository you utilize, in the case of Arch based distributions:

sudo pacman -S rtorrent

Within the /usr/share/doc/rtorrent/examples directory you will find an example config/rc file:

/usr/share/doc/rtorrent/examples/rtorrent.rc.gz

Interestingly, DT uses vim to copy it and unzip the file using vim alone (which at the time of this writing, long after having installed rtorrent, I was unaware of):

sudo nvim /usr/share/doc/rtorrent/examples/rtorrent.rc.gz

And then write it to the $HOME directory using vim's NORMAL mode:

:w /home/username/.rtorrent.rc (note the . in .rtorrent.rc)

Now let's simply change the ownership to our user:

sudo chown username:username .rtorrent.rc

And now let's edit the following lines within the rc file:

At the line:

#default.directory.set = ./

Uncomment it and reset it to Downloads:

default.directory.set = ./Downloads

We will also need a session directory to save our progress should we stop the client at any time. Simply uncomment the following line:

#session.path.set = ./session

And be sure to make that directory in your $HOME directory:

mdkir ~/session

And also uncomment the following line, which will have rtorrent "watch" for .torrent files to start torrenting:

#schedule2 = watch_directory,5,5,load.start=./watch/*.torrent

And simply create such a directory as well:

mkdir ~/watch

And that's it. now simply place an .torrent files into watch and then open up rotorrent and you are ready to go!